Not Applicable
Not Applicable
This invention is related to the field of folding chairs, especially chairs which can be collapsed into a compact position and easily transported.
Folding chairs have been designed with a rigid square back frame pivotally attached to the rear of a rigid square seat frame. These chairs typically have rigid u-shaped legs pivotally attached to the seat frame and arms. When the chair is folded the back frame folds parallel to the seat frame while the legs and arms fold parallel to the back frame. This configuration provides a chair with a rigid frame, which allows the seat material to be stretched taught between parallel frame members, and allows a mechanism which reclines the backrest of the chair to be located conveniently at the arm rests U.S. Pat. No. 5,144,03(Allen, 1894). The compactness of the chair in the folded position is, however, limited to the size of the rigid frame U.S. Pat. No. 4,514,009(Vanderminden et al, 1985).
Another type of collapsible chair consist of four sets of two tubes pivotally attached at their centers in an X position. The four sets of tubes are pivotally attached perpendicular to each other at the ends of the bars U.S. Pat. No. 3,635,520(Roher et al, 1972). This type of chair is folded by moving the legs of the chair toward one another until the legs are nearly parallel to each other. This forms a configuration in the collapsed position which is no longer limited to the size of a rigid frame. The size of this type of a collapsible chair in the folded position is only limited by the length of the back rest posts, which extend from the lower rear ends of the legs, through the upper rear leg hinges, to a position above the seat. This type of a collapsible design provides a chair that can be collapsed into a compact configuration, however, it does not incorporate some of the advantages provided by the chair with a rigid frame.
One of the disadvantages the collapsible chair has is that there is no longer a rigid frame to stretch the seat material between. Instead, the seat material is attached between the four upper corners of the legs and the weight of a seated person is used to force the legs to pivot out until the movement of the legs is restricted by the seat material. This design causes the seat to sag, because there is no rigid structure separating the leg bars. This design also causes the seat material to take more stress, since the seat material is fastened only at four concentrated points rather than being distributed along two rigid parallel members as it is with a chair with a rigid structure. Another disadvantage is that the mechanism for reclining the chair can not be located in a convenient location because there is no rigid structure on which to provide one. Instead, reclining mechanisms are located near the lower rear leg of the chair U.S. Pat. No. 6,179,374(Tang, 2001). To recline the chair the operator has to reach back to the lower portion of the legs near the back of the chair and unclip a mechanism to position the back rest bars, which pivot about the upper ends of the rear bars.
Accordingly, several objects and advantages of my invention are as follows: the chair collapses into a bundle which is not limited by the width of a rigid frame structure nor by the length of a back member. The chair provides a rigid seat frame and a rigid backrest when clipped into the open position. A rigid structure allows the seat cover material and the backrest material to be stretched taught between members which results in a more comfortable seat, and reduces the required strength of the seat material. A rigid structure also allows the reclining mechanism to be conveniently located at the arm rests. Further objects and advantages of my invention will become apparent from consideration of the drawings and ensuing description.